Solve for $x$ : $2\sqrt{x} - 10 = 9\sqrt{x} + 7$
Subtract $2\sqrt{x}$ from both sides: $(2\sqrt{x} - 10) - 2\sqrt{x} = (9\sqrt{x} + 7) - 2\sqrt{x}$ $-10 = 7\sqrt{x} + 7$ Subtract $7$ from both sides: $-10 - 7 = (7\sqrt{x} + 7) - 7$ $-17 = 7\sqrt{x}$ Divide both sides by $7$ $\frac{-17}{7} = \frac{7\sqrt{x}}{7}$ Simplify. $-\dfrac{17}{7} = \sqrt{x}$ The principal root of a number cannot be negative. So, there is no solution.